Present day computer systems are continually seeking storage methods for handling massive amounts of data with the capability of rapid and efficient retrieval of such data while still keeping down the costs and space requirements. Additionally, these systems require continuous operation with error correction capabilities for maintaining integrity of the data stored and retrieved.
Problems occur in how best to transfer data between host computers and multiple banks of disk storage units. It is desirable to relieve the host computers, as much as possible, with the burdens of managing the storage and retrieval operations to/from banks of disks. The presently described Device Interface Module (DIM) provides data transfer functions to/from disk units which relieve burdens on host computers and enhance data transfer throughout by providing multiple numbers of independent SCSI Busses which permit different concurrent data transfer cycles to be conveyed between different host computers and different disk storage units.